FREQUENTLY ASKED QUESTIONS - FAQs

Before selecting a size, it's important to first determine which generation of G-Sport catalytic converter is right for your vehicle:

GEN1 (300 CPSI Performance Catalytic ): EPA-compliant and typically suitable for vehicles 2016 and older. Gen1 will also typically keep the catalyst efficiency-related check engine lights (CEL) off in these model years.

GEN2 (400 CPSI Performance Catalytic): EPA-compliant and required to prevent catalyst efficiency-related CELs in vehicles 2017 and newer. Gen2 is compatible with all model years and is the preferred option when CEL avoidance is a priority.

Once the generation is selected, you can choose the correct converter size based on your power level:

HO – 4" Diameter (Rated up to 500 HP)

UHO – 4.5" Diameter (Rated up to 850 HP)

UHO+ – 5" Diameter (Rated up to 1,000 HP) (Gen2 only)

UHOX – 6" Diameter (Rated up to 1,200 HP) (Gen2 only)

All G-Sport converters are engineered for high performance — the difference between models comes down to power handling capability and vehicle compatibility based on emissions system sensitivity.

G-Sport by GESI catalytic converters are available in two generations and multiple performance levels, allowing you to match your emissions needs and power output with the right solution.

GEN1 vs. GEN2:

GEN1 (300 CPSI Performance Catalytic Converter ):

• EPA-compliant and typically suitable for vehicles model year 2016 and older. These converters generally prevent catalyst efficiency-related check engine lights (CELs) in earlier OBD systems.

GEN2 (400 CPSI Performance Catalytic Converter ):

• EPA-compliant and designed for 2017 and newer vehicles with more advanced emissions monitoring. Gen2 offers improved CEL prevention and overall compatibility with modern sensor strategies.

Performance Levels:

• HO (High Output) – 4" Diameter – Rated up to 500 HP
• UHO (Ultra High Output) – 4.5" Diameter – Rated up to 850 HP
• UHO+ – 5" Diameter – Rated up to 1,000 HP (Gen2 only)
• UHOX – 6" Diameter – Rated up to 1,200 HP (Gen2 only)

All G-Sport catalytic converters are high-performance rated. The primary differences between models are horsepower capability and emissions system compatibility.

What is a Mid-Bed Cat?

A Mid-Bed cat is a specific type of GEN2 catalytic converter that contains two separate catalyst bricks within a single housing, with an oxygen sensor port located between them. This mirrors the design commonly found in many OEM catalytic converters.

We developed the Mid-Bed option to offer customers a high-performance, emissions-compliant replacement that maintains the physical and functional characteristics of factory catalytic systems — while benefiting from GESI's proven durability and flow performance.

Mid-Bed converters are available in:

• 4.5" Diameter (UHO Mid-Bed)
• 5.0" Diameter (UHO+ Mid-Bed)

Each size is offered as either a substrate-only unit (no cones) or with 3" transition cones, giving fabricators multiple integration options.

G-Sport catalytic converters are engineered to meet EPA standards and are designed to work with factory oxygen sensor feedback systems. However, CEL behavior depends on the vehicle’s model year and the sensitivity of its emissions system:

GEN2 (400 CPSI) converters are designed to prevent catalyst efficiency-related CELs, especially in 2017 and newer vehicles, which utilize more advanced OBD monitoring.

GEN1 (300 CPSI) converters typically function without triggering a CEL in vehicles 2016 and older, where post-cat O2 sensor thresholds are less aggressive.

For the highest likelihood of avoiding a CEL, the catalytic converter should be installed in the OEM location or as close to the original placement as possible. Placing the converter too far downstream may prevent it from reaching optimal operating temperature — and since catalytic converters require heat to effectively convert exhaust gases, cooler temperatures can reduce efficiency and increase the chance of triggering a fault code.

While our GEN2 converters greatly reduce the risk, no aftermarket converter can absolutely guarantee CEL prevention due to variations in factory calibration, sensor behavior, and vehicle condition.

G-Sport by GESI high-performance catalytic converters are designed to meet EPA emissions standards and are legal for use on federally registered vehicles outside of California and other CARB-regulated states. While our converters deliver excellent emissions performance, they are not CARB-certified and are not currently approved for use on emissions-controlled vehicles in California.

It’s also important to note that we offer four part numbers that are not EPA-compliant. These converters are listed under the “OBD2 G-Sport Emissions Catalytic Converters” category on our website and include:

• 10025
• 10030
• 12030
• 12230

These are intended for custom and motorsport applications where emissions compliance is not required.

Regarding European standards, our GEN2 performance catalytic converters often meet or exceed the emissions performance thresholds defined under Euro 6 standards. We are currently working toward formal certification for use in European markets.

In summary:

✅ EPA-compliant (Except for the above-listed part numbers)

❌ Not CARB-certified (Not legal for sale or use on public roads in California)

In dual-bank systems, it’s important to use the same catalytic converter model on both banks to ensure balanced flow and consistent O2 sensor readings. Mixing different converter generations or sizes from one bank to another can cause uneven backpressure and may trigger a check engine light (CEL) due to inconsistent catalyst efficiency data.

That said, there are certain cases where using two different converter models within the same bank is acceptable:

• If your exhaust setup uses two catalytic converters per bank, you can run different models in the primary (monitored) and secondary (unmonitored) positions.
• For vehicles model year 2017 and newer, the primary converter should be Gen2 to help prevent catalyst efficiency-related CELs.
• The secondary converter, which is not monitored by the O2 sensors, can be a Gen1 — even on newer vehicles. This is a common configuration for customers looking to maximize flow while maintaining emissions compliance.
• Gen1 converters offer a slight flow advantage due to their lower 300 CPSI density, making them a good fit for secondary positions.

Summary:

❌ Do not mix models between banks in a dual-bank setup

✅ It is acceptable to mix models within the same bank if the primary converter is Gen2 on 2017+ vehicles

For optimal performance and emissions efficiency, G-Sport high-flow catalytic converters should be placed as close to the original factory location as possible. Proper placement is especially important for maintaining catalyst light-off temperatures and preventing check engine lights (CELs) related to catalyst efficiency.

Here are some general guidelines:

• Avoid placing the catalytic converter too far downstream, as cooler exhaust temperatures may reduce the converter’s ability to properly activate and maintain efficiency.
• If you're building a custom system, aim to install the converter within 8–24 inches of the turbo outlet or header collector (or closer, if possible).
• For modern OBD2 vehicles, especially 2017 and newer, placement is critical — post-cat O2 sensors expect to see a specific temperature and reaction pattern, and moving the cat too far back can affect emissions readings.
• All G-Sport converters are designed for durability, but correct placement ensures you get the most from your converter in terms of both performance and emissions compliance.

Each G-Sport by GESI catalytic converter is laser-etched with a part number on the center body of the converter. This part number helps identify the model, generation, and performance rating.

You can reference any part number that appears on our retail products directly on our website for specifications and fitment information.

If the part number begins with HPPL (which stands for High Performance Private Label), this means the converter was manufactured specifically for an exhaust system manufacturer and will not be listed on our website. Internal coating specifications may vary across different HPPL models depending on the partner's application.

However, you can still identify the horsepower rating of any G-Sport converter by measuring its overall diameter, which follows the same guide as our retail lineup:

• 4" Diameter – Rated up to 500 HP
• 4.5" Diameter – Rated up to 850 HP
• 5" Diameter – Rated up to 1,000 HP
• 6" Diameter – Rated up to 1,200 HP

If the laser etching is no longer visible, feel free to contact us with measurements and photos, and we can help you identify the closest match.

Yes  - G-Sport by GESI offers dealer and distributor account options for qualified businesses. We work directly with performance exhaust manufacturers, fabricators, speed shops, and jobbers who are looking to integrate or resell our high-performance catalytic converters.

Benefits of becoming a dealer or distributor include:

• Access to wholesale pricing
• Bulk ordering options and improved margins
• Dedicated product support and technical guidance
• Priority access to new product launches and inventory updates

To apply for a dealer or distributor account, please fill out the form on our contact page.

Once we receive your inquiry, a member of our team will follow up to review your eligibility and account setup.

Yes, G-Sport by GESI offers international shipping to most countries, including the USA, Canada, Australia, and the European Union. Orders can be placed directly through our website, and international shipping rates will be calculated at checkout based on your location and order size.

Important Notice for International Customers:

Please note that orders shipping outside of North America may incur additional brokerage charges or import fees upon receipt of your product. These charges are determined by the destination country's customs regulations and are the responsibility of the recipient. We recommend checking with your local customs office for more information on these potential costs.

If you experience any issues during checkout, such as address formatting errors or shipping restrictions — feel free to contact us for assistance.